Many in this thread mention that a pet peeve is people not reading the prior posts in the thread. At this other site that's the 15/15 rule. You need to read 15 pages of a thread, (some of their threads have 60 pages for one topic). They set up this rule because they feel everyone's time is valuable, and no one is more important than the others. Of course, people still can skim, and some probably don't read it, but they do give warnings to people who ask a question that has been answered 52 times prior to their post. Or announce, "I haven't read the other posts but..." Actually, they will go as far to delete such a post.
Also mentioned here is the multiple topics on the same thing. TPTB at the other site insist that you search all topics in the drop down window or by using the "Show All Topics" link. Then if there is no topic, you can start a new one. It's a totally different set up there, so it's not as overwhelming as I'm making it sound.